Words are the foundation of all of our knowledge, man. They both allow for and encapsulate our understanding (Wittgenstein paraphrase). Why don't you give me an example of a better way to transmit information than through words, one that could have been applied throughout history?
And it's not that they didn't read it properly, it's that they simply don't care and scammed people. Even if they had read it, which they probably didn't, they wouldn't care. They don't believe in any of it, so why would they care? They just know other people do and they're easy prey. Evangelical megachurches and their priests all know what's up, they simply don't care. Rapey, pedophilic priests knew what was up. The leaders of the Crusades, with strong financial interests, knew what was up. It's not a "no true Scotsman", it's more like "if I'm raping a child and you find me and I tell you I'm a good moral man, a believer who's afraid of God's judgment, and you believe me, you're mentally challenged". And many people are, I guess.
And btw, it's not that "my morality is the only morality", is that moral standards exist independently of our whims and our ability to see quickly and clearly them, I just happen to be able to see it and admit it to myself. Even when I transgress, I know I am doing so and I feel bad about it, and it allows me to get better. Many people don't even have the notion of transgressing in their minds: if they like it, they'll do it. Even if they rationalize it and do it, they only halfway admit to themselves they're doing something wrong (because without the objective standards established by God, the Norths [you might go a bit northwest and be right, but never go south and be right about things], are you doing something wrong, really? The postmoderns say it's just a matter of perspective, lol). But you can't argue against God. And I'm not alone (not that it matters necessarily but just for the record), since most of the world believes in objective moral truths, this problem is mostly just a thing in the postmodern West. And some religious people, by themselves or with different degrees of divine inspiration, have made it abundantly clear for everyone, because they're too entranced with Love Island to think about their lives and actions critically so God did us a solid and communicated things we always had the responsibility to explore.